Bollinger Bands [ChartSchool] - StockCharts.com

Technical Tools for Traders | Bollinger Bands | Measuring

%B = (Price - Lower Band)/(Upper Band - Lower Band) The default setting for %B is based on the default setting for Bollinger Bands (20,2). The bands are set 2 standard deviations above and below the 20-day simple moving average, which is also the middle band. Security price is the close or the last trade.